The present invention relates to a processs for manufacturing a plasma ignition device for an internal combustion engine, adapted particularly for igniting poor and/or hydrogenated and/or activated mixtures by catalysts, comprising an insulating body wherein there is provided an axial central bore receiving an axial metal central electrode, and a metal base comprising an axial central bore accommodating the lower portion of said insulating body and for securely fixing the device to the engine block. It also relates to an ignition device resulting from such process.
At the present time, searchers devote their efforts to extending the useful operating range of internal combustion engines of cars having much poorer or leaner fuel mixtures, allowing an increase of engine efficiency with a reduced consumption, while decreasing the combustion temperatures and reducing thereby the emission of NO . It has been established that under a certain poor mixture, the output of the engine decreases and the proportion of misfirings increases exponentially until combustion ceases completely. It is believed that one of the reasons for such problems comes from the fact that the output is limited by the speed of the flame which slows down as the mixture becomes poorer and poorer. Efforts have been made to solve such problems, for example, by means of brazing techniques, by turbulence, and by providing multiple ignition points. However, all these conceptions require a certain degree of transformation and modification of the engines. In general, efforts have been limited by the shape of the conventional spark-plug.
The study of the ignition process as a field susceptible of improvements has led to the finding that means to ignite a poor mixture in a more reliable way could be provided by increasing the discharged energy and/or displacing the ignition core through the combustion-chamber by means of electro-magnetic forces. The first results show that such a system could be realized by the fact that a small mixture volume is ionised, and brought to a very high temperature by means of a high energy pulse discharge. The plasma volume ignited is pushed into the main combustion-chamber by self-induction forces.
This idea has been applied under a certain aspect in the HONDA CIVIC AUTOMOBILE engine, which requires a new cylinder head and a third valve in a combustion prechamber where a small volume of a rich mixture is ignited and acts as a torch or burner to ignite the poor or lean mixture in the main chamber. The disadvantage of such system is that it requires a complete transformation of the engine which must be fitted with a special cylinder-head.